The invention relates generally to apparatus for photopolymerization. More particularly, the invention relates to apparatus for producing three dimensional objects by irradiating uncured photopolymeric material to solidify the photopolymeric material.
It is known to create three dimensional objects by building up layers of photopolymeric material. See, for example, "Rapid Prototyping Systems," Mechanical Engineering, April 1991, pp. 34-43, incorporated herein by reference. See also, for example, U.S. Pat. No. 4,752,498, issued to Fudim on Jun. 21, 1988 and incorporated herein by reference. That patent also discloses that, when creating three dimensional objects by building up layers of photopolymeric material, it is advantageous to employ, in contact with the photopolymeric material, a transparent member which does not substantially interfere with subsequent linking of photopolymeric material from one layer to another layer, and which transparent member can be removed after an irradiation of a layer. To increase the size of the three dimensional object being created, after irradiation of a first layer, the transparent member is removed from the first layer, more photopolymeric material is added on top of the first layer, the transparent member is placed on top of and in contact with the newly added photopolymeric material, and the photopolymeric material is irradiated from above the transparent member. The transparent member is disclosed as being a glass plate 13 with a coating 23 thereunder, or such as a stretched transparent film of the material of the coating 23. The coating 23 is of a material which leaves the irradiated upper surface of photopolymeric material capable of further cross-linking. The disclosed preferred material for the coating 23 is fluorinated ethylene propylene copolymer.